1. Field of the Invention
The present invention relates in general to shells of various shapes with a diamond covering, and more particularly to a method/system for producing substantially spherical nanocrystalline diamond shells often having a desired surface roughness at the nanometer level.
2. Description of Related Art
Sphere-like bearings are often subjected to radial loads in conventional configurations, often in configurations wherein the bearings undergo rolling motions and are maintained at an equivalent distance from each other. Since the sliding friction is extremely small, these bearings are frequently used in a rotary section of various types of machines.
Sphere-like shells having nuclear disposed fuel therein are also utilized for controlled thermonuclear fusion to address solutions to long term energy shortage problems. One problem in releasing fusion energy is to confine an intense hot plasma, for example, plasma of hydrogen isotopes deuterium-tritium, long enough for fusion reactions to take place. One technique, called laser fusion, utilizes high powered lasers to implode small fuel pellets, for example pellets of hydrogen isotopes deuterium-tritium, to thousands of times their normal liquid density and thereby initiate a fusion reaction. The laser light is focused onto a low density atmosphere of material as it evaporates from the surface of the pellet. This light is absorbed in the plasma atmosphere by electron-ion collisions or by plasma instabilities. In both cases the hot electrons travel in toward the center of the pellet and heat the pellet surface. The surface cools itself by ablation, i.e., by rapidly expelling material. This material traveling outward creates an equal and opposite force which compresses the pellet. The compression continues until the pressure created is greater than the ablation force.
One of the problems encountered in laser fusion is that plasma instabilities due to using high powered lasers tend to create extremely energetic electrons. These electrons can penetrate the core of the fuel pellet prematurely, thus making compression more difficult; a phenomenon called “preheat”. These electrons also have a long range and therefore reduce the heat transfer between the pellet surface and the plasma atmosphere which results in uneven heating of the pellet, known as “decoupling”.
The threshold for plasma instabilities can be increased by using hollow fuel shells. In such a case, the ablation pressure acts for a longer time and over a larger area and volume, so that less laser intensity is needed for implosion. However, a problem exists in producing hollow fuel pellets, ideally hollow spheres of the fuel material, which are of consistently uniform size, shape and thickness.
Accordingly, a need exists for an improved method/system for producing articles to be utilized in various applications that requires the covering be a hard material which resists abrasive degradation, with significant chemical stability, and is able to absorb large mechanical stresses or be optically transparent. The present invention is directed to such a need.